1. Field of the Invention
The present invention relates to an anthracene-based compound and an organic light emitting device employing the same, and more particularly, to an anthracene-based compound including a pyridinylquinoline-based group or a pyridinylisoquinoline-based group and an organic light emitting device including an organic layer formed of the anthracene-based compound.
2. Description of the Related Art
Organic light emitting devices are active light emitting display devices that emit light by recombination of electrons and holes in a thin layer made of a fluorescent or phosphorescent organic compound (an organic layer) when a current is applied to the organic layer. The organic light emitting devices have advantages such as lightweight, simple constitutional elements, an easy fabrication process, superior image quality and a wide viewing angle. Furthermore, the organic light emitting devices can accomplish perfect creation of dynamic images and high color purity. The organic light emitting devices also have electrical properties, such as low power consumption and low driving voltage, suitable for portable electronic equipment
A multi-layered organic light emitting device using an aluminum quinolinol complex layer and a triphenylamine derivative layer was developed by Eastman Kodak Co. (U.S. Pat. No. 4,885,211), and a wide range of light from ultraviolet lights to infrared lights can be emitted using low-molecular weight materials when an organic emitting layer is formed (U.S. Pat. No. 5,151,629).
Light emitting devices, which are self light emitting display devices, have wide viewing angles, excellent contrast and a quick response. Light emitting devices are classified into inorganic light emitting devices using inorganic compounds to form emitting layers and organic light emitting devices (OLED) using organic compounds to form emitting layers. Organic light emitting devices have higher brightness, lower driving voltages and quicker responses than inorganic light emitting devices and can realize multi colors. Thus, organic light emitting devices have been actively studied.
Typically, an organic light emitting device has an anode/organic emitting layer/cathode structure. An organic light emitting device can also have various other structures, such as an anode/hole injection layer/hole transport layer/emitting layer/electron transport layer/electron injection layer/cathode structure or an anode/hole injection layer/hole transport layer/emitting layer/hole blocking layer/electron transport layer/electron injection layer/cathode structure.
Materials that are used in organic light emitting devices can be classified into vacuum deposited materials and solution coated materials according to a method of preparing an organic layer. The vacuum deposited materials may have a vapor pressure of 10-6 torr or greater at the temperature of 500° C. or less and may be low molecular materials having a molecular weight of 1200 or less. The solution coated materials may be highly soluble in solvents to be prepared in solution phase, and include aromatic or heterocyclic groups.
When an organic light emitting device is manufactured by vacuum deposition, costs may be increased due to expensive vacuum systems and high resolution pixels may not be easily manufactured if a shadow mask is used to prepare pixels for a natural color display. On the other hand, an organic light emitting device can be easily and inexpensively manufactured using solution coating such as inkjet printing, screen printing and spin coating and can have relatively high resolution compared to when using a shadow mask.
Meanwhile, when a conventional organic light emitting device is operated or stored at a high temperature, emitting light may be changed, light emitting efficiency may be reduced, driving voltages may be increased, and lifetime may be shortened. In order to prevent those problems, a novel electron transport material having a high glass transition temperature (Tg) and capable of reducing driving voltage needs to be developed.
Oxadiazole derivatives, triazole derivatives, phenanthroline derivatives and aluminum complexes are widely used as an electron transport material. In particular, research on an electron transport material using a phenanthroline-based or bipyridine-based compound is vigorously performed.
International Publication No. WO2007/026847 discloses a compound having a triazole ring structure substituted with a pyridyl group, and Japanese Patent Publication No. hei 15-123983 discloses a 1,10-phenanthroline-based compound to manufacture organic light emitting devices having low driving voltage and high efficiency by using higher electron transporting capability compared to conventional electron transport materials.